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A proteomic survey of microtubule-associated proteins in a R402H TUBA1A mutant mouse

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2020

PLoS Genet. 2020 Nov 2;16(11):e1009104. doi: 10.1371/journal.pgen.1009104. eCollection 2020 Nov.

A proteomic survey of microtubule-associated proteins in a R402H TUBA1A mutant mouse

I Leca;AW Phillips;I Hofer;L Landler;L Ushakova;TD Cushion;G Dürnberger;K Stejskal;K Mechtler;DA Keays

Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), Vienna, Austria. Institute of Zoology, University of Natural Resources and Life Sciences (BOKU), Vienna, Austria. Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Vienna, Austria. Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna Biocenter (VBC), Vienna, Austria. Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia. Division of Neurobiology, Department Biology II, Ludwig-Maximilians-University Munich, Planegg-Martinsried 82152, Germany.

Service type: Knock-in mice

Abstract

Microtubules play a critical role in multiple aspects of neurodevelopment, including the generation, migration and differentiation of neurons. A recurrent mutation (R402H) in the α-tubulin gene TUBA1A is known to cause lissencephaly with cerebellar and striatal phenotypes. Previous work has shown that this mutation does not perturb the chaperone-mediated folding of tubulin heterodimers, which are able to assemble and incorporate into the microtubule lattice. To explore the molecular mechanisms that cause the disease state we generated a new conditional mouse line that recapitulates the R402H variant. We show that heterozygous mutants present with laminar phenotypes in the cortex and hippocampus, as well as a reduction in striatal size and cerebellar abnormalities. We demonstrate that homozygous expression of the R402H allele causes neuronal death and exacerbates a cell intrinsic defect in cortical neuronal migration. Microtubule sedimentation assays coupled with quantitative mass spectrometry demonstrated that the binding and/or levels of multiple microtubule associated proteins (MAPs) are perturbed by the R402H mutation including VAPB, REEP1, EZRIN, PRNP and DYNC1l1/2. Consistent with these data we show that the R402H mutation impairs dynein-mediated transport which is associated with a decoupling of the nucleus to the microtubule organising center. Our data support a model whereby the R402H variant is able to fold and incorporate into microtubules, but acts as a gain of function by perturbing the binding of MAPs.

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